is eating at late night bad?

Not really. If you have low blood sugar before going to bed it is recommended.

And no you don't gain weight. From midnight of one day to midnight the next day you expend energy and you take in food for energy over 24 hrs.So It doesn't matter when you do either.

Yes, if you go to sleep immediately, because when you lay down, the digestive system doesn't work as well and it contributes to fat build up.

No, if you don't sleep 2 hours after eating.

I'm no expert I only know what my doctor tells me. If you eat after midnight your body often stores whatever you eat as FAT

It can cause weight gain. I wouldn't worry about it though if you have a fast metabolism.

You will gain weight.

Depends on who your with?

No

No.